At present, personal authentication techniques using an image including a person's face have been put into practical use. In such personal authentication techniques, the collation between face images having different postures is one of great technical problems.
Regarding such a problem, methods are disclosed in which face images different from an input face image are generated and collated by using a three-dimensional shape model of a face.
For example, Patent Document 1 discloses a method of acquiring a two-dimensional image and three-dimensional face shape information of a person serving as a subject, and collating the person in the two-dimensional image, using two-dimensional features obtained by correcting two-dimensional image texture on the basis of posture and shape change information between a standard model which is a three-dimensional model of a general face prepared in advance and the acquired three-dimensional face shape information, and three-dimensional feature points obtained from the three-dimensional face shape information.
In addition, Patent Document 2 discloses a method in which, after the posture of a face is estimated using a stable feature point regardless of a person, other feature points conspicuously exhibiting differences for each person are converted into specific postures using a three-dimensional shape model of a standard face, and collation is performed by comparing feature amounts of positions of the other feature points.
In addition, Patent Document 3 discloses a method of generating a partial region image in which partial regions in the vicinity of feature points are deformed so as to be set to the same orientation of a face as a reference image face, on the basis of feature points disposed on a standard three-dimensional shape model of a face, feature points of a face in an input image, and information of the orientation of a face in the input image, and collating the partial region image with the reference image.